Improvement in flexible shafts for dental engines



Patented Dec. 29, l874.-

No.l58,3f25.

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UNITED STATES PATENT OFFICE.

ELI T. STARR, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR TO SAMUEL S. WHITE, OF SAME PLACE.

IMPROVEMENT IN FLEXIBLE SHAFTS FOR DENTAL ENGINES.

Specification forming part of Letters Patent No. 158,325, dated December 29, 1874; application filed DecemberwrlflLlSZfLmu CAsE B.

To all whom it may concern:

Be it known that I, ELI T. STARR, of the city and county of Philadelphia, in the State of Pennsylvania, have invented an Improved Flexible Shaft for Dental Engines, of which the following is a specification The object of my invention is to secure a rotating shaft for transmitting powerfrom the prime mover to the operating tool, which shall be capable of flexing freely Without interrupting the transmission ot' the driving-power, while sufliciently rigid against torsional strains.

The coiled-wiresprin g cables or shafts heretofore used for this purpose have been found in practice to possess defects which it. is my object to remove; to which end my improvement consists in combining a cable with an envelope of rubber, gutta-percha, or equivalent material, which closely embraces and rotates with the cable.

In the accompanying drawings, Figure 1 shows a view, partly in section, ofmy improved nexible shaft, connected with the hand-pieces of a dental engine. Fig. 2 represents a simi-j 2, or of a series of pin-jointed slotted links, as shown in Fig. 3. This latter. form of cable is not, however, herein claimed per se, as it forms the subject-matter of Letters Patent granted to me December 8, 1874.

This central Ebre or cable is inclosed b v well-known means within a closely-adhering engvelope, B, composed of rubber o-gittapereha, whicl"forms an integral part of the shaft, and of course rotatesavith it. In practice T'have found this shaf't to possessfgreat flexibility and capacity for transmitting mo tion steadily, and Without springing or jumping. to dispense with a non-rotating flexible sheath heretofore employed, thus simplifying the cost of the mechanism and lessening its liability to 4 derangement, while avoiding the danger of entangling the hair of the patient with the rotating shaft. I claiml The flexible shaft hereinbefore set forth, consisting of the combination of a exible metallic cable and a closely-adhering envelope ot' rubber or gutta-percha.

In testimony whereof l have hereunto subscribed my name.

ELI T. STARR. Witnesses:

J As. B. WILLIAMS, FRANK L. HIsE.

I am also enabled by this construction l 

